[英]can't write dom document to xml file
我在上载xml文件并尝试通过DOM将其写入我的xml的spring mvc项目中,但是遇到了这个异常。 当我尝试在常规项目中执行相同的过程时,一切正常。 无法理解为什么会发生..
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is java.lang.NullPointerException
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:894)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789)
javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
root cause
java.lang.NullPointerException
org.apache.xml.utils.TreeWalker.dispatachChars(TreeWalker.java:303)
org.apache.xml.utils.TreeWalker.startNode(TreeWalker.java:447)
org.apache.xml.utils.TreeWalker.traverse(TreeWalker.java:202)
org.apache.xalan.transformer.TransformerIdentityImpl.transform(TransformerIdentityImpl.java:343)
com.mycompany.xmlloader.xmlHandler.DOMParser.saveToCatalog(DOMParser.java:147)
com.mycompany.xmlloader.service.XMLServiceImpl.updateCatalog(XMLServiceImpl.java:48)
com.mycompany.xmlloader.controller.XMLController.uploadToCatalog(XMLController.java:47)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.lang.reflect.Method.invoke(Method.java:601)
org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:213)
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:126)
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:96)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:617)
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:578)
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923)
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852)
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882)
org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789)
javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
和代码段:
TransformerFactory transfac = TransformerFactory.newInstance();
Transformer trans = transfac.newTransformer();
trans.setOutputProperty(OutputKeys.OMIT_XML_DECLARATION, "yes");
trans.setOutputProperty(OutputKeys.INDENT, "yes");
StreamResult result = new StreamResult(catalogFile.toURI().getPath());
Source source = new DOMSource(doc);
trans.transform(source, result);
问题的可能原因是Document
的“ Text
节点,其数据设置为null
。 (有关此问题的讨论,请参见此处和此处 。)
您可以使用以下代码检查Document
以查看此诊断是否正确:
public static void checkDoc(Node n) {
if (n instanceof Text) {
if (((Text) n).getData() == null) {
System.err.println("null data!!!!");
}
}
NodeList l = n.getChildNodes();
for (int i = 0; i < l.getLength(); ++i) {
checkDoc(l.item(i));
}
}
在您的Document
上调用checkDoc
:
checkDoc(doc);
如果看到任何输出,则现在知道NPE的直接原因。 然后,解决问题的方法是:不要构建包含具有空数据的Text
节点的Document
。
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